Snare

ABSTRACT

A snare for snaring an article in a vessel of a vascular system or other body vessel. The snare includes a core cable having a proximal end portion and a distal end portion. The snare also includes first, second and third loops each having a proximal end portion and a distal end portion, and a mid-portion therebetween formed by spaced apart first and second sides connected together at the distal end portion of the loop. The mid-portions of each of the loops cross over mid portions of one of the other two loops, and the loops are only connected together at their proximal end portions, where they are gathered together and attached to the distal end portion of the core cable. The loops are movable between an open position and a closed position.

BACKGROUND

Various instruments are used for removing foreign objects from the bodyof a patient. For example, such instruments may be used for removal ofstones such as kidney stones, gallstones, and the like from varioussites along the urinary tract of a patient's body. Retrieval devices arealso widely used for removing foreign articles from the vascular systemof a patient. In such cases, examples of the foreign articles includevascular stents, vena cava filters, and parts of medical devices such ascatheters, guide wires, cardiac leads, or the like, which may break andbecome detached during medical procedures or need removal for otherreasons.

Some types of these instruments employ a collapsible wire basketarranged within a flexible catheter formed as a tubular sheath adaptedto penetrate body passages to reach the location where the object is tobe evacuated. Another known type of retrieval device for use within abody vessel is a “snare” configured as one or more distal loops which,in operation, may be positioned over a free end of the foreign body, andwhich may be collapsed and tightened around the foreign body so that itmay be retrieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of one embodiment of an intravascularsnare.

FIG. 2 is a side view of the intravascular snare shown in FIG. 1.

FIG. 3 is a top view of the intravascular snare shown in FIGS. 1 and 2.

FIG. 4 is a detail view of a portion indicated by dashed circle 4 ofFIG. 3.

FIG. 5 is a front elevational view of one loop of the intravascularsnare shown in FIGS. 1 and 2.

FIG. 6 is a side elevational view of one loop of the intravascular snareshown in FIGS. 1 and 2.

FIG. 7 is a side perspective view of the intravascular snare shown inFIGS. 1 and 2 in an open position during operation in a vessel of avascular system.

FIG. 8 is a side view of the intravascular snare shown in FIGS. 1 and 2in a partially closed position during operation in a vessel of avascular system.

FIG. 9 is a side view of the intravascular snare shown in FIGS. 1 and 2in a fully closed position during operation in a vessel of a vascularsystem.

DETAILED DESCRIPTION

An intravascular snare 10 according to one embodiment is shown in FIGS.1 and 2. The snare 10 includes a first loop 12, a second loop 14, and athird loop 16 that are each coupled to a core cable 17 (or “core wire”)having a proximal end portion and a distal end portion 19. Morespecifically, each of the loops 12, 14, and 16 includes a proximal endportion 12 a, 14 a, and 16 a, respectively, that are gathered togetherand coupled to the distal end portion 19 of the core cable 17. Further,each of the loops 12, 14, and 16 includes a distal end portion 12 b, 14b, and 16 b, respectively, spaced away from and positioned forward ofthe corresponding proximal end portion 12 a, 14 a, and 16 a of the loop.Each of the loops 12, 14, and 16 also includes a mid-portion 12 d, 14 d,and 16 d, respectively, on a first side and a mid-portion 12 c, 14 c,and 16 c, respectively, on a spaced-apart second side of the loop spacedbetween the proximal end portion 12 a, 14 a, and 16 a and the distal endportion 12 b, 14 b, and 16 b, respectively, of the loop.

Each of the loops 12, 14, and 16 may be formed from a solid ormulti-strand material. In some embodiments the loops 12, 14, and 16 areformed from a multi-strand composite of nitinol wire and platinum wire(e.g., five strands of nitinol wire and two strands of platinum wire) sothat the platinum wire provides radiopacity while the nitinol wireprovides shape memory and/or superelastic characteristics. The multiplestrands forming the loops 12, 14, and 16 may be braided, knitted, woven,wound, or the like. As can be appreciated, other material(s) may be usedfor the loops 12, 14, and 16 as well. The proximal end portions 12 a, 14a, and 16 a of the loops 12, 14, and 16 may be fixedly coupled to thedistal end portion 19 of the core cable 17 by a soldering process.Further, a stainless steel ferrule 18 may be crimped over the solderjoint connecting the proximal end portions 12 a, 14 a, and 16 a of theloops 12, 14, and 16 to the distal end portion 19 of the core cable 17to provide a secure connection. In some embodiments, the core cable 17may be formed from a solid strand of nitinol wire, but the core cablemay also be formed from other materials and/or multiple strands of oneor more materials. The core cable 17 may also be tapered at the distalend 19 to reduce the resulting cross-sectional area of the couplingregion between the core cable 17 and the loops 12, 14, and 16.Additionally, the core cable 17 may be formed by rearward extension ofthe wires forming the loops 12, 14, and 16, thus eliminating the need tosolder the loops 12, 14, and 16 to a separate core cable.

For each of the loops 12, 14, and 16, the distal end portion 12 b, 14 b,and 16 b, respectively, is positioned forward of the proximal endportion 12 a, 14 a, and 16 a, respectively, and the mid-portion extendslaterally outwardly relative to the distal end 19 of the core cable 17.Further, the distal end portion of each of the loops 12, 14, and 16curve forwardly away from the mid-portions thereof. The specific shapeof the loops 12, 14, and 16 may best be viewed in FIGS. 5 and 6, whichillustrate a front view (FIG. 5) and a side view (FIG. 6) of the firstloop 12, which is representative of the second loop 14 and the thirdloop 16. As shown in FIG. 6, the mid-portion 12 d, as well as themid-portion 12 c, of the loop 12 extends laterally outward from theproximal end portion 12 a at an angle α. Preferably, the angle α isbetween about 90 and 150 degrees (e.g., 130 degrees), but it is not solimited. Further, when viewed from the side as in FIG. 6, the distal endportion 12 b curves forwardly away from the mid-portion 12 d (andmid-portion 12 c). As best seen in FIG. 5, the distal end portion 12 bhas an arcuate shape that forms what may be referred to as a “ski tip.”The “ski tip” shape of the distal end portions 12 b, 14 b and 16 b mayhelp guide the loops 12, 14, and 16 forward during advancement in a bodyvessel, thereby reducing the likelihood that the loops will bendbackward during advancement causing the snare to have a diminishedeffectiveness. That is, the “ski tip” deflects against the walls of abody vessel which allows the distal end portions 12 b, 14 b and 16 b toslide along the walls during advancement and prevents “digging” into thewalls. As discussed below with reference to FIGS. 7 and 8, the shape andconfiguration of the loops 12, 14, and 16 provide a snare that iseffectively functional to capture articles (e.g., stents, filters,medical components, or the like) positioned within a vessel of avascular system or other body vessel. In this example, the loops 12, 14,and 16 are substantially identical in size and shape, however, it willbe appreciated that different numbers, sizes, and shapes may be used forthe loops of a snare.

FIG. 3 illustrates a top view of the intravascular snare 10 shown inFIGS. 1 and 2, and FIG. 4 illustrates a detail view of the portion ofFIG. 3 indicated by the dashed circle 4. As shown in FIG. 3, themid-portion 12 d (the first side) of the first loop 12 and themid-portion 14 c (the second side) of the second loop 14 are arrangedwith one crossing over each other (when viewed as shown in FIG. 3) at acrossover point 20, with the mid-portion 14 c being inward of themid-portion 12 d. Further, the mid-portion 14 d (the first side) of thesecond loop 14 and the mid-portion 16 c (the second side) of the thirdloop 16 are arranged with one crossing over each other at a crossoverpoint 22, with the mid-portion 16 c being inward of the mid-portion 14d. Similarly, the mid-portion 16 d (the first side) of the third loop 16and the mid-portion 12 c (the second side) of the first loop 12 arearranged with one crossing over each other at a crossover point 24, withthe mid-portion 12 c being inward of the mid-portion 16 d. In thisexample, each of the crossover points 20, 22, and 24 are positioned at alocation away from the proximal end portions of each of the respectiveloops 12, 14, and 16 by about 40-60 percent of the length of the totaldistance between the proximal end portion and the distal end portionthereof. As can be appreciated, the specific locations of the crossoverpoints 20, 22, and 24 as well as the degree of overlap between the loops12, 14, and 16 may be selected dependent on a particular application.

Further, it is noted that the loops 12, 14, and 16 are not connected toeach other at the crossover points 20, 22, and 24, or elsewhere exceptat their proximal end portions. This feature permits each of the loops12, 14, and 16 to move independently of each other, thereby improvingthe ability of the snare 10 to capture articles in a vessel of avascular system or other body vessel. Further, this feature includes amanufacturing and/or cost advantage over designs that include interlacedor connected loops by not including complex connection points.

The configuration in the illustrated embodiment for the gathering of theproximal end portions 12 a, 12 b, and 12 c of the loops 12, 14, and 16at the distal end 19 of the core cable 17 may best be viewed in FIG. 4.As can be appreciated, the proximal end portions of the loops 12, 14,and 16 around the circumference of the distal end 19 of the core cable17 are positioned to produce the overlapping feature such that thecrossover points 20, 22, and 24 are provided. It is noted that thedashed lines shown in FIG. 4 are provided to show the positioning of theproximal end portions 12 a, 12 b, and 12 c of the loops 12, 14, and 16,respectively, and do not represent a particular shape for the loops 12,14, and 16.

FIG. 4 also shows a distal end 31 of an elongate sheath 30 (shown inFIGS. 7 and 8). The sheath 30 may be sized to receive the core cable 17and the loops 12, 14, and 16 when the loops are inserted or retractedinto the sheath. Further, the sheath 30 is operative to be inserted intoa vessel of a vascular system or other body vessel so that a portion ofthe vessel may be accessed by the intravascular snare 10. The sheath 30may be any suitable length, such as 100 centimeters, 200 centimeters, orother length. The sheath 30 may comprise a special or generic flexiblecatheter formed from any suitable material, such as polyvinyl chloride(PVC), flouropolymer, polyurethane with a hydrophilic coating, or otherbiocompatible material.

FIGS. 7, 8 and 9 illustrate the operation of the intravascular snare 10inside a vessel 40 of a vascular system. In this example, the sheath 30may be introduced percutaneously into a vessel (e.g., the femoralartery). The sheath 30 may be injected with radio-opaque dye orotherwise include a radio-opaque marker that can be seen on live X-rayor fluoroscopy so that it may be guided to a position of the vessel 40where the snare 10 is to be used to retrieve a vena cava filter 50 orother article inside the vessel. As shown in FIG. 7, the loops 12, 14,and 16 extend outwardly from the distal end portion 31 of the sheath 30.This position of the snare 10 relative to the sheath 30 may generally bereferred to as the “open position.” In the open position, the loops 12,14, and 16 extend laterally outwardly with their distal end portions inan open position and define a space therebetween for receiving at leasta portion of the article therein. When in the open position, preferablythe distal end portion 12 b of the loop 12 contacts a first wall portion40 a of the vessel 40 at a point 42. Similarly, the distal end portion16 b of the loop 16 contacts a second wall portion 40 b of the vessel 40at a point 44, and the distal end portion 14 b of the loop 14 contacts athird wall portion (not shown) of the vessel 40. The force exerted onthe wall portions is generally not sufficient to deform the wallportions. As can be appreciated, the shape of the loops 12, 14, and 16when in the open position may allow for a “sledding effect” along thewalls of the vessel 40 which enable the snare 10 to capture articlespositioned at or near the walls.

In operation, a user may selectively manipulate the position of the corecable 17 relative to the sheath 30 to move the snare 10 between the openposition (FIG. 7), a partially closed position (FIG. 8), and a fullyclosed or collapsed position (FIG. 9). Such positioning of the corecable 17 and the sheath 30 relative to each other may involve moving thecore cable 17 rearward or forward (as indicated by arrow 46), moving thesheath 30 rearward or forward (as indicated by arrow 48), or both. Inthe partially closed position, the loops 12, 14, and 16 are positionedlaterally inwardly from their open position with their distal endportions 12 b, 14 b, and 16 b in a closed position sufficiently closertogether than when in the open position to grasp between one or more ofthe loops 12, 14, and 16 at least a portion of the vena cava filter 50in the space.

This manipulation is illustrated by the arrows 46 and 48 shown in FIGS.7 and 8, respectively, near a proximal end 17 a of the core cable 17 anda proximal end 30 a of the sheath 30. In the open position, the loops12, 14, and 16 may have substantially the shape shown in FIGS. 1-6,depending on the inner diameter of the vessel 40. As a user adjusts theposition of the core cable 17 relative to the sheath 30, the loops arepulled toward and into the distal end 31 of the sheath 30 causing themto move inward and collapse in on each other as shown in FIG. 8 untilthe loops are fully collapsed together as shown in FIG. 9. As can beappreciated, by selectively transitioning the loops 12, 14, and 16between the open position and the closed position, a user may retrievearticles such as the vena cava filter 50 positioned inside the vessel40. Further, the arcuate distal ends 12 b, 14 b, and 16 b of the loops12, 14, 16 arc laterally inwardly as the loops 12, 14, and 16 are movedinto the closed position, thereby further increasing the ability of thesnare 10 to retrieve articles. In addition to manipulating the positionof the core cable 17 and the sheath 30 relative to each other asindicated by the arrows 46 and 48, the core cable 17 (and therefore theloops 12, 14, and 16) may be rotated by a user in a clockwise orcounterclockwise direction (as indicated by arrow 47). As can beappreciated, rotating the core cable 17 clockwise may have a tendency toglide the loops 12, 14, and 16 along the wall of the vessel 40, androtating the core cable 17 counterclockwise may help drive the loops 12,14, and 16 toward the side wall and help to grab articles adjacent tothe wall of the vessel 40.

The foregoing embodiments described herein depict different componentscontained within, or connected with, different other components. It isto be understood that such depicted architectures are merely exemplary,and that in fact many other architectures can be implemented whichachieve the same functionality. In a conceptual sense, any arrangementof components to achieve the same functionality is effectively“associated” such that the desired functionality is achieved. Hence, anytwo components herein combined to achieve a particular functionality canbe seen as “associated with” each other such that the desiredfunctionality is achieved, irrespective of architectures or intermedialcomponents. Likewise, any two components so associated can also beviewed as being “operably connected,” or “operably coupled,” to eachother to achieve the desired functionality.

While particular embodiments have been shown and described, it will beobvious to those skilled in the art that, based upon the teachingsherein, changes and modifications may be made without departing fromthis invention and its broader aspects and, therefore, the appendedclaims are to encompass within their scope all such changes andmodifications as are within the true spirit and scope of this invention.Furthermore, it is to be understood that the invention is solely definedby the appended claims. It will be understood by those within the artthat, in general, terms used herein, and especially in the appendedclaims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term “including” should be interpreted as“including but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes but is not limited to,” etc.). It will be further understoodby those within the art that if a specific number of an introduced claimrecitation is intended, such an intent will be explicitly recited in theclaim, and in the absence of such recitation no such intent is present.For example, as an aid to understanding, the following appended claimsmay contain usage of the introductory phrases “at least one” and “one ormore” to introduce claim recitations. However, the use of such phrasesshould not be construed to imply that the introduction of a claimrecitation by the indefinite articles “a” or “an” limits any particularclaim containing such introduced claim recitation to inventionscontaining only one such recitation, even when the same claim includesthe introductory phrases “one or more” or “at least one” and indefinitearticles such as “a” or “an” (e.g., “a” and/or “an” should typically beinterpreted to mean “at least one” or “one or more”); the same holdstrue for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, those skilled in the art willrecognize that such recitation should typically be interpreted to meanat least the recited number (e.g., the bare recitation of “tworecitations,” without other modifiers, typically means at least tworecitations, or two or more recitations).

Accordingly, the invention is not limited except as by the appendedclaims.

1. (canceled)
 2. (canceled)
 3. The snare of claim 19, wherein the firstside of the first loop and the second side of the second loop cross overthe other at a location away from the proximal end portion of each byabout 40-60 percent of the length of the total distance between theproximal end portion and the distal end portion thereof, first side ofthe second loop and the second side of the third loop cross over theother at a location away from the proximal end portion of each by about40-60 percent of the length of the total distance between the proximalend portion and the distal end portion thereof, and the first side ofthe third loop and the second side of the first loop cross over theother at a location away from the proximal end portion of each by about40-60 percent of the length of the total distance between the proximalend portion and the distal end portion thereof.
 4. The snare of claim19, wherein the first, second and third loops each have substantiallythe same length from its proximal end portion to its distal end portion.5. The snare of claim 19, wherein the distal end portion of each of thefirst, second and third loops has an arcuate shape.
 6. The snare ofclaim 19, wherein the first, second and third loops each has at leastone of a shape memory and a superelastic characteristic.
 7. The snare ofclaim 19, wherein each of the first, second and third loops is formedfrom multiple strands of material.
 8. The snare of claim 19, furthercomprising: an elongate sheath adapted to penetrate into a body vesseland sized to receive the core cable and the first, second and thirdloops, the elongate sheath including a distal end having an opening suchthat the first, second and third loops may be retracted within thesheath and protracted therefrom by selectively manipulating the proximalend portion of the core cable relative to the sheath.
 9. (canceled) 10.(canceled)
 11. (Cancelled)
 12. The snare of claim 20, wherein each ofthe first, second and third loops is attached to the core cable bysolder.
 13. The snare of claim 20, wherein each of the first, second andthird loops is attached to the core cable by a crimped ferrule.
 14. Thesnare of claim 20, wherein the core cable is formed from a nitinol wirethat is tapered near the distal end portion of the core cable.
 15. Thesnare of claim 19, wherein the first, second and third loops havesubstantially identical shapes.
 16. (canceled)
 17. The snare of claim20, wherein the first, second and third loops when in the open positionextend laterally outwardly and forward with the mid-portions of thefirst, second and third loops at an angle from 90 to 150 degreesrelative to the distal end portion of the core cable.
 18. The snare ofclaim 19, wherein the second side of the second loop is positionedinward of the first side of the first loop at the a first crossoverpoint, and wherein the second side of the third loop is positionedinward of the first side of the second loop at the a second crossoverpoint, and wherein the second side of the first loop is positionedinward of the first side of the third loop at the a third crossoverpoint.
 19. A snare for snaring an article, comprising: first, second andthird loops, each of the first, second and third loops having a proximalend portion and a distal end portion, and a mid-portion therebetween,and being formed by spaced apart first and second sides connectedtogether at the distal end portion of the loop, the distal end portionsbeing positioned forward of the proximal end portions, the first side ofthe first loop and the second side of the second loop being arrangedwith one crossing over the other and being disconnected, the first sideof the second loop and the second side of the third loop being arrangedwith one crossing over the other and being disconnected, and the firstside of the third loop and the second side of the first loop beingarranged with one crossing over the other and being disconnected, thedistal end portions of the first, second and third loops beingdisconnected from each other, the first, second and third loops beingmovable between an open position whereat the first, second and thirdloops extend laterally outwardly with their distal end portions in anopen position and define a space therebetween for receiving at least aportion of the article therein, and a collapsed position whereat thefirst, second and third loops are positioned laterally inwardly fromtheir open position with their distal end portions in a closed positioncloser together than when in the open position, and the mid-portions ofthe first, second and third loops being disconnected from each other topermit independent movement of each as the first, second and third loopsare moved between the open and closed positions.
 20. The snare of claim19, further comprising: a core cable having a proximal end portion and adistal end portion, wherein the proximal end portions of the first,second and third loops are gathered together and attached to the distalend portion of the core cable.
 21. The snare of claim 19, wherein thedistal end portion of each of the first, second and third loops curvesforwardly away from the mid-portion thereof.
 22. (canceled) 23.(canceled)
 24. A method for snaring an article inside a body vessel,comprising: inserting a snare into the body vessel, the snarecomprising: a core cable having a proximal end portion and a distal endportion; first, second and third loops, each of the first, second andthird loops having a proximal end portion and a distal end portion, anda mid-portion therebetween, and being formed by spaced apart first andsecond sides connected together at the distal end portion of the loop,the distal end portions being positioned forward of the proximal endportions, the first side of the first loop and the second side of thesecond loop being arranged with one crossing over the other and beingdisconnected, the first side of the second loop and the second side ofthe third loop being arranged with one crossing over the other and beingdisconnected, and the first side of the third loop and the second sideof the first loop being arranged with one crossing over the other andbeing disconnected, the distal end portions of the first, second andthird loops being disconnected from each other, the proximal endportions of the first, second and third loops being gathered togetherand attached to the distal end portion of the core cable, the first,second and third loops being movable between an open position whereatthe first, second and third loops extend laterally outwardly with theirdistal end portions in an open position and define a space therebetweenfor receiving at least a portion of the article therein, and a collapsedposition whereat the first, second and third loops are positionedlaterally inwardly from their open position with their distal endportions in a closed position closer together than when in the openposition, and the mid-portions of the first, second and third loopsbeing disconnected from each other to permit independent movement ofeach as the first, second and third loops are moved between the open andclosed positions; and an elongate sheath adapted to penetrate into abody vessel and sized to receive the first, second and third loops, theelongate sheath including a proximal end and a distal end having adistal end opening; selectively manipulating at least one of theproximal end of the core cable and the proximal end of the elongatesheath to selectively retract the first, second and third loops withinthe distal end opening and to selectively protract the first, second andthird loops from the distal end opening.
 25. The method of claim 24,further comprising: selectively rotating the proximal end of the corecable relative to the elongate sheath to effect a rotation of the first,second and third loops.
 26. The method of claim 25, wherein selectivelyrotating the proximal end of the core cable relative to the elongatesheath includes rotating in one of clockwise and counterclockwisedirections to move the first, second and third loops outward toward awall of the body vessel, and rotating the other of clockwise andcounterclockwise directions to move the first, second and third loopsinward away from a wall of the body vessel.
 27. The method of claim 24,wherein the distal end portion of each of the first, second and thirdloops curves forwardly away from the mid-portion thereof, the methodfurther comprising: advancing the snare in a forward direction throughthe body vessel such that the distal end portion of each of the first,second and third loops slide along walls of the body vessel.
 28. Thesnare of claim 19, wherein each of the first, second and third loops isformed from multiple strands of wires including at least one of nitinolwire and wire comprising radiopaque material.